[gnome-shell] switcherPopup: Show immediately on second key press

[Florian Müllner <fmuellner src gnome org>]

commit 9132063b877c8daf4eede22e98a6624402395334
Author: Florian Müllner <fmuellner gnome org>
Date:   Thu Nov 21 23:40:02 2019 +0100

    switcherPopup: Show immediately on second key press
    
    We slightly delay showing the switcher popup to avoid flashing it
    briefly in the common case of quickly switching back-and-forth
    between two windows.
    
    However some users perceive this delay as slowness. Address this by
    showing the popup immediately when another key press is consumed
    (that is, a key like Tab is pressed).
    
    https://gitlab.gnome.org/GNOME/gnome-shell/issues/1928

 js/ui/switcherPopup.js | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)
---
diff --git a/js/ui/switcherPopup.js b/js/ui/switcherPopup.js
index 85e962ef2c..44228ec1b3 100644
--- a/js/ui/switcherPopup.js
+++ b/js/ui/switcherPopup.js
@@ -139,15 +139,24 @@ var SwitcherPopup = GObject.registerClass({
             GLib.PRIORITY_DEFAULT,
             POPUP_DELAY_TIMEOUT,
             () => {
-                Main.osdWindowManager.hideAll();
-                this.opacity = 255;
-                this._initialDelayTimeoutId = 0;
+                this._showImmediately();
                 return GLib.SOURCE_REMOVE;
             });
         GLib.Source.set_name_by_id(this._initialDelayTimeoutId, '[gnome-shell] Main.osdWindow.cancel');
         return true;
     }
 
+    _showImmediately() {
+        if (this._initialDelayTimeoutId === 0)
+            return;
+
+        GLib.source_remove(this._initialDelayTimeoutId);
+        this._initialDelayTimeoutId = 0;
+
+        Main.osdWindowManager.hideAll();
+        this.opacity = 255;
+    }
+
     _next() {
         return mod(this._selectedIndex + 1, this._items.length);
     }
@@ -167,8 +176,10 @@ var SwitcherPopup = GObject.registerClass({
 
         this._disableHover();
 
-        if (this._keyPressHandler(keysym, action) != Clutter.EVENT_PROPAGATE)
+        if (this._keyPressHandler(keysym, action) != Clutter.EVENT_PROPAGATE) {
+            this._showImmediately();
             return Clutter.EVENT_STOP;
+        }
 
         // Note: pressing one of the below keys will destroy the popup only if
         // that key is not used by the active popup's keyboard shortcut